Piezoelectric device, liquid ejecting head, and liquid ejecting apparatus

ABSTRACT

A piezoelectric device used in a liquid ejecting head that ejects a liquid from a nozzle includes a flow-path-forming substrate in which an individual liquid chamber that communicates with the nozzle and a liquid supply chamber that communicates with the individual liquid chamber are formed, a vibration plate formed at a position corresponding to the individual liquid chamber and the liquid supply chamber of the flow-path-forming substrate, a plurality of liquid supply ports formed in the liquid supply chamber, and a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode, the piezoelectric element being formed at a position on the vibration plate corresponding to the individual liquid chamber, where the liquid supply ports are provided so as to penetrate the vibration plate, and where the vibration plate contains zirconium oxide.

BACKGROUND 1. Technical Field

The present invention relates to a piezoelectric device including apiezoelectric element, a liquid ejecting head including thepiezoelectric device, and a liquid ejecting apparatus provided with theliquid ejecting head.

2. Related Art

An example of a piezoelectric device used in an ink jet recording head,which is a typical example of a liquid ejecting head, is a piezoelectricdevice including a flow-path-forming substrate provided with anindividual flow path communicating with a nozzle and provided with aliquid supply chamber communicating with the individual flow path, and apiezoelectric element provided on one surface side of theflow-path-forming substrate via a vibration plate.

A configuration has been disclosed for an ink jet recording head havingsuch a piezoelectric device in which a plurality of liquid supply portscommunicating with a liquid supply chamber are provided on a vibrationplate, which allows the vibration plate to have a filter function (see,for example, JP-A-2013-000993).

However, in the case where liquid supply ports are formed in thevibration plate, there is a problem that the vibration plate is easilydamaged because ink supply pressure is applied to the vibration plate.

Therefore, in JP-A-2013-000993, the vibration plate that forms theliquid supply port is formed by stacking many layers, whereby theinternal stress of the vibration plate is regulated in order to suppressthe damage to the vibration plate. However, when a large number oflayers are stacked on one another and the vibration plate becomes thick,the flexure of the piezoelectric element is impeded and the displacementcharacteristic deteriorates.

Further, such a problem exists not only in the ink jet recording headbut also in a piezoelectric device used in a liquid ejecting head whichejects a liquid other than ink.

SUMMARY

An advantage of some aspects of the invention is that a piezoelectricdevice, a liquid ejecting head, and a liquid ejecting apparatus in whichdamage to a film around liquid supply ports is suppressed withoutimpeding displacement of the piezoelectric element are provided.

A piezoelectric device according to a first aspect of the invention usedin a liquid ejecting head that ejects a liquid from a nozzle includes aflow-path-forming substrate in which an individual liquid chamber thatcommunicates with the nozzle and a liquid supply chamber thatcommunicates with the individual liquid chamber are formed, a vibrationplate formed at a position corresponding to the individual liquidchamber and the liquid supply chamber of the flow-path-formingsubstrate, a plurality of liquid supply ports formed in the liquidsupply chamber, and a piezoelectric element including a first electrode,a piezoelectric layer, and a second electrode, the piezoelectric elementbeing formed at a position on the vibration plate corresponding to theindividual liquid chamber, where the liquid supply ports are provided soas to penetrate the vibration plate, and where the vibration platecontains zirconium oxide.

A liquid ejecting head according to a second aspect of the inventionincludes the piezoelectric device of the first aspect.

A liquid ejecting apparatus according to a third aspect of the inventionincludes the liquid ejecting head according to the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is an exploded perspective view of a recording head according toan embodiment of the invention.

FIG. 2 is a plan view of the recording head.

FIG. 3 is a cross-sectional view of the recording head.

FIG. 4 is an enlarged cross-sectional view of a main portion of therecording head.

FIG. 5 is a diagram illustrating a schematic configuration of arecording apparatus.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the drawings. However, the following description merelyillustrates an embodiment of the invention, and it can be arbitrarilychanged within the scope of the invention. In addition, in the drawings,the same reference numerals are given to the same members, andexplanations thereof are omitted as appropriate. In each figure, X, Y,and Z represent three spatial axes orthogonal to each other. In thepresent specification, directions along these axes will be described asa first direction X, a second direction Y, and a third direction Z.

Embodiment

FIG. 1 is an exploded perspective view of an ink jet recording headaccording to an embodiment of the invention, which is an example of aliquid ejecting head, FIG. 2 is a plan view of the ink jet recordinghead, FIG. 3 is a cross-sectional view taken along line III-III of FIG.2, and FIG. 4 is an enlarged view of the main portion of FIG. 3.

As illustrated in the figures, a flow-path-forming substrate 10constituting an ink jet recording head 1 (hereinafter, also simplyreferred to as a recording head 1) can be formed of a metal such asstainless steel or Ni, a ceramic material such as ZrO₂ or Al₂O₃, a glassceramic material, an oxide such as SiO₂, MgO, or LaAlO₃, or the like. Inthis embodiment, the flow-path-forming substrate 10 is formed of asingle-crystal silicon substrate.

The flow-path-forming substrate 10 is anisotropically etched from onesurface side so that pressure-generating chambers 12 partitioned by aplurality of partition walls 11 are parallelly arranged along the firstdirection X in which a plurality of nozzles 21 for ejecting ink areparallelly arranged. In addition, in the flow-path-forming substrate 10,ink supply paths 14 and communication paths 15 are partitioned by thepartition walls 11 on one end side of the pressure-generating chambers12 in the second direction Y. That is, in this embodiment, theflow-path-forming substrate 10 is provided with the pressure-generatingchambers 12, the ink supply paths 14, and the communication paths 15 asindividual flow paths communicating with the nozzles 21, respectively.

In addition, at one end of the communication paths 15 in the seconddirection Y, a communication portion 13 to be a common liquid chamber ofeach of the pressure-generating chambers 12 is formed. In thisembodiment, the communication portion 13 is a liquid supply chamber thatsupplies ink to the individual flow paths. That is, theflow-path-forming substrate 10 is provided with liquid flow pathsincluding the pressure-generating chambers 12, the communication portion13, the ink supply paths 14, and the communication paths 15.

The ink supply paths 14 are formed with a narrower width than thepressure-generating chambers 12 in the first direction X and keep theflow path resistance of the ink flowing from the communication portion13 into the pressure-generating chambers 12 constant. Further, the inksupply paths 14 are not limited to being formed with a narrow width andthe height in the third direction Z may be decreased.

A nozzle plate 20 having the nozzles 21 communicating with the vicinityof an end portion of corresponding ones of the pressure-generatingchambers 12 on the opposite side to the ink supply paths 14 is fixed byan adhesive, a heat welding film, or the like on the surface side of theflow-path-forming substrate 10 at which the pressure-generating chambers12 open. Further, the nozzle plate 20 is formed of a glass ceramic, asingle-crystal silicon substrate, stainless steel or the like.

On the other hand, a vibration plate 50 is formed on the surface of theflow-path-forming substrate 10 on the opposite side to the nozzle plate20. The vibration plate 50 of this embodiment includes an elastic film51 containing silicon oxide provided on the flow-path-forming substrate10 side and an insulating film 52 containing zirconium oxide provided onthe elastic film 51. Further, liquid flow paths such as those of thepressure-generating chambers 12 are formed by anisotropic etching of theflow-path-forming substrate 10 from the surface side of theflow-path-forming substrate 10 to which the nozzle plate 20 is joinedand the surface of the pressure-generating chambers 12 on the oppositeside to the nozzle plate 20 is defined by the elastic film 51.

Further, the elastic film 51 containing silicon oxide (SiO₂) can beformed, for example, by thermally oxidizing the flow-path-formingsubstrate 10 formed of a single-crystal silicon substrate. In theelastic film 51 containing silicon oxide formed in this way, theinternal stress is a compressive stress. That is, in this embodiment,the elastic film 51 is a compressive stress film whose internal stresshas compressive stress. In addition, the material of the elastic film 51which is the compressive stress film is not limited to silicon oxide,and for example, silicon nitride (SiN), titanium oxide (TiO_(x)) or thelike may be used. That is, the elastic film 51 is a single layer or amultilayer body of at least one kind of material selected from siliconoxide (SiO₂), silicon nitride (SiN), and titanium oxide (TiO_(x)). Ofcourse, the method of manufacturing the elastic film 51 is not limitedto the above-mentioned one, and it can also be formed by a gas phasemethod or a liquid phase method. In addition, the elastic film 51 is notlimited to a film having an internal stress that is a compressivestress, and may be a film having an internal stress that is a tensilestress.

The insulating film 52 containing zirconium oxide can be formed by avapor phase method such as a sputtering method or a chemical vapordeposition method (CVD method) or a liquid phase method such as asol-gel method, or a metal-organic decomposition (MOD) method.

For example, by forming the insulating film 52 by a gas phase method, itis possible to form a zirconium layer having columnar or nearly columnarcrystals (here, collectively referred to as columnar crystals in bothcases). Specifically, after forming a zirconium layer formed ofzirconium (Zr) by a gas phase method, zirconium oxide (ZrO₂) can beformed by thermally oxidizing this zirconium layer. At this time, byadjusting the temperature at the time of thermally oxidizing thezirconium layer, the stress of zirconium oxide can be adjusted, and thetensile stress increases as the sintering temperature is raised. Inaddition, zirconium oxide may be formed by a reactive sputtering method.In this case, zirconium oxide having a compressive stress is formed.Because the internal stress of the elastic film 51 containing siliconoxide is a compressive stress, by setting the internal stress of theinsulating film 52 as a tensile stress and adjusting the tensile stress,the internal stress of the vibration plate 50 around liquid supply ports16, which will be described in detail later, is made neutral, and thedamage to the vibration plate 50 around the liquid supply ports 16 iseasily suppressed.

Further, the insulating film 52 deposited by the gas phase method has acrystal structure in which columnar grains are densely assembled, and itis possible to satisfactorily suppress the diffusion of lead (Pb) from apiezoelectric layer 70.

In addition, by forming the insulating film 52 by a liquid phase method,a zirconium oxide layer having granular crystals can be formed. Asdescribed above, the insulating film 52 of zirconium oxide formed by theliquid phase method has a tensile stress as an internal stress. Inaddition, the zirconium oxide layer formed by the liquid phase methodcan be a flexible film having a crystal structure in which smalldiameter particles are sparsely assembled and having a small Young'smodulus. Therefore, the displacement amount of the insulating film 52,that is, the displacement amount of the vibration plate 50 can beincreased. Consequently, it is preferable to include zirconium oxidehaving granular crystals.

In addition, a zirconium oxide layer formed by a vapor phase method anda zirconium oxide layer formed by a liquid phase method may be combined.Consequently, this makes it easy to adjust the internal stress of theinsulating film 52. In other words, by stacking a zirconium oxide layerwith a tensile internal stress generated by a vapor phase method and azirconium oxide layer with a compressive internal stress generated by aliquid phase method, it is also possible to adjust the internal stressesso as to cancel each other. Consequently, the internal stress of thevibration plate 50 around the liquid supply ports 16, which will bedescribed in detail later, is made neutral, and damage to the vibrationplate 50 around the liquid supply ports 16 is easily suppressed.

Further, the formation of the zirconium oxide layer having the granularcrystals is not limited to a liquid phase method and the zirconium oxidelayer having the granular crystals may instead be formed by a gas phasemethod, in addition, the formation of the zirconium oxide layer havingcolumnar crystals is not limited to a gas phase method and the zirconiumoxide layer having columnar crystals may instead be formed by a liquidphase method.

In addition, the insulating film 52 containing zirconium oxidepreferably has a tetragonal or cubic crystal structure. That is, it ispreferable to use stabilized (partially stabilized) zirconia obtained byadding a rare earth oxide such as yttrium oxide, calcium oxide,magnesium oxide, hafnium oxide or the like to zirconium oxide, morepreferably, yttria-stabilized zirconia (YSZ), that is, it is preferablethat the insulating film 52 containing zirconium oxide contains yttrium.By using stabilized (partially stabilized) zirconia as described above,tetragonal or cubic crystals are stabilized even at room temperature,the toughness of the insulating film 52 can be further enhanced, thetoughness of the vibration plate 50 can be increased, and it is possibleto suppress damage to the vibration plate 50 around the liquid supplyports 16, which will be described in detail later.

In addition, in this embodiment, the elastic film 51 and the insulatingfilm 52 are provided as the vibration plate 50; however, the inventionis not limited thereto, and only the insulating film 52 may be providedas the vibration plate 50. In addition, another film may be provided inaddition to the elastic film 51 and the insulating film 52 serving asthe vibration plate 50.

In addition, on the vibration plate 50 of the flow-path-formingsubstrate 10, a first electrode 60, the piezoelectric layer 70, and asecond electrode 80 are stacked by a film deposition and lithographymethod to form piezoelectric elements 300. In this embodiment, thepiezoelectric elements 300 serve as pressure-generating units forgenerating a pressure change in the ink in the pressure-generatingchambers 12. Here, the piezoelectric elements 300 are also referred toas piezoelectric actuators and are units including the first electrode60, the piezoelectric layer 70, and the second electrode 80. In general,one of the electrodes of the piezoelectric element 300 is used as acommon electrode common to the plurality of the piezoelectric elements300, and the other electrode is configured as an independent individualelectrode for each of the piezoelectric elements 300. In thisembodiment, the first electrode 60 is used as a common electrode and thesecond electrode 80 is used as an individual electrode, but these may bereversed.

The first electrode 60 is a material capable of maintaining conductivitywithout oxidizing when the piezoelectric layer 70 is being deposited,for example, a noble metal such as platinum (Pt) or iridium (Ir), orconductive oxides represented by lanthanum nickel oxide (LNO), iridiumoxide (IrO₂) and the like, and, furthermore, a multi-layer film formedof the aforementioned may be suitably used.

In addition, as the first electrode 60, an adhesion layer for securingadhesion strength between the above-described conductive material andthe vibration plate 50 may be used. In this embodiment, although notspecifically illustrated, titanium is used as the adhesion layer.Further, as the adhesion layer, zirconium, titanium, titanium oxide, orthe like can be used. That is, in this embodiment, the first electrode60 is formed of an adhesion layer made of titanium and at least oneconductive layer selected from the above-described conductive materials.

The piezoelectric layer 70 is formed of an oxide piezoelectric materialhaving a polarization structure formed on the first electrode 60, forexample, the piezoelectric layer 70 can be formed of a perovskite typeoxide represented by the general formula ABO₃, or a lead-basedpiezoelectric material containing lead, a lead-free piezoelectricmaterial not containing lead, or the like can be used. The piezoelectriclayer 70 can be formed by a liquid phase method such as a sol-gel methodor a metal-organic decomposition (MOD) method, a physical vapordeposition (PVD) method (gas phase method) such as a sputtering methodor laser ablation method, or the like.

The second electrode 80 is preferably formed of a material capable ofsatisfactorily forming an interface with the piezoelectric layer 70 andcapable of exhibiting conductivity and piezoelectric characteristics,and a noble metal material such as iridium (Ir), platinum (Pt),palladium (Pd), or gold (Au), or a conductive oxide typified bylanthanum nickel oxide (LNO) may be suitably used. In addition, thesecond electrode 80 may be a multi-layer body formed of a plurality ofmaterials. In this embodiment, a multi-layer electrode of iridium andtitanium (where iridium is in contact with the piezoelectric layer 70)is used. The second electrode 80 can be formed by a physical vapordeposition (PVD) method (gas phase method) such as a sputtering methodor a laser ablation method, a liquid phase method such as a sol-gelmethod, a metal-organic decomposition (MOD) method, or a plating method,or the like. In addition, after formation of the second electrode 80, byperforming heat treatment, the characteristics of the piezoelectriclayer 70 can be improved.

The second electrode 80 such as that described above is formed only onthe piezoelectric layer 70, that is, only on the surface of thepiezoelectric layer 70 on the opposite side to the flow-path-formingsubstrate 10.

In addition, the piezoelectric element 300 is covered with a protectivefilm 200. As the protective film 200, an insulating material havingmoisture resistance can be used. In this embodiment, the protective film200 is provided so as to cover the side surface of the piezoelectriclayer 70, and the side surface and peripheral portion of the uppersurface of the second electrode 80. That is, the protective film 200 isnot provided in the main portion of the second electrode 80, which isthe substantially central region of the upper surface of the secondelectrode 80, and an opening portion 201 that exposes the main portionof the second electrode 80 is provided.

The opening portion 201 is an opening that opens in a rectangular shapealong the second direction Y of the piezoelectric element 300 bypenetrating the protective film 200 in the third direction Z, which isthe thickness direction; for example, the opening portion 201 can beformed by forming the protective film 200 over the entire surface of theflow-path-forming substrate 10 and patterning the protective film 200.

By covering the side surface of the piezoelectric layer 70 of thepiezoelectric element 300 with the protective film 200 as describedabove, leakage of current between the first electrode 60 and the secondelectrode 80 can be suppressed and damage to the piezoelectric element300 can be suppressed. In addition, by providing the opening portion201, it is possible to restrain the displacement of the piezoelectricelement 300 from being significantly lowered by the protective film 200.As a material of the protective film 200 such as that described above,any material having moisture resistance may be used, and an inorganicinsulating material, an organic insulating material, or the like can beused.

Examples of the inorganic insulating material usable as the protectivefilm 200 include silicon oxide (SiO_(x)), zirconium oxide (ZrO_(x)),tantalum oxide (TaO_(x)), aluminum oxide (AlO_(x)), and titanium oxide(TiO_(x)). As the inorganic insulating material of the protective film,in particular, aluminum oxide (AlO_(x)), which is an inorganic amorphousmaterial, for example, alumina (Al₂O₃), is preferably used. Further, theprotective film 200 formed of an inorganic insulating material can beformed by, for example, an MOD method, a sol-gel method, a sputteringmethod, a CVD method, or the like.

In addition, as the organic insulating material usable as the protectivefilm 200, for example, at least one selected from an epoxy resin, apolyimide resin, a silicone resin, and a fluorine resin can be used.Further, the protective film 200 formed of an organic insulatingmaterial can be formed by, for example, a spin coating method, a spraymethod, or the like.

A lead electrode 90 formed of, for example, gold (Au) or the like isprovided on the protective film 200. One end of the lead electrode 90 isconnected to the second electrode 80 via a communication hole 202provided in the protective film 200 and the other end thereof extends toan end portion of the flow-path-forming substrate 10 on the oppositeside to the ink supply path 14, and the extended tip portion isconnected to a drive circuit 120 that drives the piezoelectric element300, which will be described later, via a connection wire 121.

Furthermore, a protective substrate 30 having a manifold portion 31 forsupplying ink to the communication portion 13 is joined to the surfaceof the flow-path-forming substrate 10 on the piezoelectric element 300side. In this embodiment, the flow-path-forming substrate 10 and theprotective substrate 30 are joined using an adhesive 35. The manifoldportion 31 of the protective substrate 30 communicates with thecommunication portion 13 via a plurality of the liquid supply ports 16,and the ink from the manifold portion 31 is supplied to thecommunication portion 13 via the plurality of the liquid supply ports16.

A plurality of the liquid supply ports 16 that supply the ink from themanifold portion 31 to the communication portion 13 are provided in thevibration plate 50.

Each of the liquid supply ports 16 has an opening smaller than theopening on the communication portion 13 side of the manifold portion 31and at least two or more liquid supply ports 16 are provided. Here, “aplurality of the liquid supply ports 16 are provided” means that two ormore liquid supply ports 16 are provided for one communication portion13. For example, in the case where two or more communication portions 13are provided in the flow-path-forming substrate 10, it is sufficient fora plurality of the liquid supply ports 16 to be provided for each of thecommunication portions 13. That is, although a plurality of the liquidsupply ports 16 are provided in the vibration plate 50, the case whereone liquid supply port 16 is provided for one communication portion 13is not included in the meaning of “plurality of supply ports” of theinvention. By providing two or more liquid supply ports 16 in onecommunication portion 13, the vibration plate 50 is provided in the formof a canopy over the opening of the communication portion 13 on theprotective substrate 30 side.

The liquid supply ports 16 such as those described above penetrate thevibration plate 50. Here, “the liquid supply ports 16 penetrate thevibration plate 50” means that the insulating film 52 containingzirconium oxide that forms the vibration plate 50 is provided at leastin a portion around the liquid supply ports 16. That is, “the insulatingfilm 52 containing zirconium oxide that forms the vibration plate 50 isprovided at least in a portion around the liquid supply ports 16” refersto a configuration in which the insulating film 52 that forms thevibration plate 50 is continuously provided in the circumferentialdirection of one liquid supply port 16 as well as a configuration inwhich the insulating film 52 that forms the vibration plate 50 isprovided discontinuously in the circumferential direction of one liquidsupply port 16. In addition, “the insulating film 52 is provided atleast in a portion around the liquid supply ports 16” refers to aconfiguration in which the insulating film 52 forms a portion of theopening edge portion of the liquid supply ports 16, a configuration inwhich the insulating film 52 is formed in a portion between adjacentones of the liquid supply ports 16, and a configuration in which theinsulating film 52 is formed in a portion between the liquid supplyports 16 and the flow path wall. In this embodiment, the elastic film 51and the insulating film 52 are continuously formed in the peripheraledge of the opening edge portion of the liquid supply ports 16.

The vibration plate 50 provided with a plurality of the liquid supplyports 16 functions as a filter that captures foreign bodies such asbubbles and dust contained in the ink when supplying ink from themanifold portion 31 to the communication portion 13. Because thevibration plate 50 that is provided with the plurality of the liquidsupply ports 16 and that functions as a filter in this way, is providedin an eaves shape at the opening of the communication portion 13 on theprotective substrate 30 side, it is not supported by theflow-path-forming substrate 10 when pressure is applied by the inksupplied from the manifold portion 31 to the communication portion 13.However, by using the insulating film 52 containing zirconium oxidehaving high toughness as the vibration plate 50, even if the vibrationplate 50 that is provided in the opening of the communication portion 13flexes, it is possible to suppress the occurrence of damage such ascracks in the vibration plate 50. In particular, in this embodiment, theinsulating film 52 containing zirconium oxide that forms the vibrationplate 50 is continuously formed in the circumferential direction of theliquid supply ports 16. By providing the insulating film 52 continuouslyin the circumferential direction of the liquid supply ports 16 in such amanner, it is possible to further suppress the formation of cracks inthe vibration plate 50 over the entire circumference in thecircumferential direction of the liquid supply ports 16. In the casewhere a vibration plate having low toughness is provided in a regionwhere the communication portion 13 and the manifold portion 31communicate with each other and the liquid supply ports 16 are providedin the vibration plate 50, the internal stress of the vibration plate 50and the pressure of the ink causes damage such as cracks in thevibration plate 50. In this embodiment, by using the insulating film 52containing zirconium oxide having high toughness for the vibration plate50 provided in the region where the communication portion 13 and themanifold portion 31 communicate with each other, damage such as cracksand the like in the vibration plate 50 due to the internal stress of thevibration plate 50 and ink pressure can be suppressed. Therefore, it ispossible to realize the recording head 1 with high reliability.

Here, the fracture toughness values of zirconium oxide, silicon nitride,and silicon oxide are shown in Table 1 below.

TABLE 1 Fracture Toughness Value Vibration Plate Material [MPa ·m^(0.5)] Zirconium Oxide (ZrO₂) 7 to 8 Silicon Nitride (Si₃N₄) 5 SiliconOxide (SiO₂) 3

As illustrated in Table 1, the toughness of zirconium oxide is largerthan that of silicon nitride or silicon oxide. Therefore, by using theinsulating film 52 containing zirconium oxide having high toughness forthe vibration plate 50 provided in the region where the communicationportion 13 and the manifold portion 31 communicate with each other,damage such as cracks and the like in the vibration plate 50 due to theinternal stress of the vibration plate 50 and ink pressure can besuppressed.

In addition, in this embodiment, because the insulating film 52containing zirconium oxide is used as the vibration plate 50, it is notnecessary to form the vibration plate 50 to be relatively thick with athree-layer to ten-layer multi-layer structure and it is possible torestrain the vibration plate 50 from impeding the displacement of thepiezoelectric element 300.

By making the vibration plate 50 under the piezoelectric element 300 andthe vibration plate 50 forming the liquid supply ports 16 differentmaterials or different multi-layer structures, although damage to thevibration plate 50 in the portion where the liquid supply ports 16 areformed can be suppressed, the manufacturing process is lengthened andthe cost is increased. In this embodiment, by providing the portion ofthe vibration plate 50 overlapping with the piezoelectric element 300and the portion of the vibration plate 50 where the liquid supply ports16 are formed when viewed in plan from the third direction Zcontinuously in the same layer, an increase in the number ofmanufacturing operations can be suppressed, and the cost can be reduced.

In addition, because the vibration plate 50 has high toughness by usingthe insulating film 52 containing zirconium oxide, even if the vibrationplate 50 around the liquid supply ports 16 is flexed by the pressurefluctuation in the communication portion 13, cracks are unlikely tooccur. Therefore, the vibration plate 50 around the liquid supply ports16 can be flexed by pressure change in the communication portion 13, andthe pressure fluctuation in the communication portion 13 can beabsorbed. Therefore, it is also possible to reduce the size of oreliminate the compliance portion to be described later in detail.

Further, in this embodiment, the flow-path-forming substrate 10, thevibration plate 50, and the piezoelectric element 300 provided in thepressure-generating chamber 12 and the like are collectively referred toas a piezoelectric device.

On the other hand, a piezoelectric-element-holding portion 32 isprovided in a region of the protective substrate 30 that faces thepiezoelectric element 300. Because the piezoelectric element 300 isformed in the piezoelectric-element-holding portion 32, thepiezoelectric element 300 is protected in a state in which it is hardlyaffected by the external environment. Further, thepiezoelectric-element-holding portion 32 may be sealed or not sealed.

As a material of the protective substrate 30 such as that describedabove, for example, a glass, a ceramic material, a metal, a resin, orthe like can be used, for example, it is preferable that the protectivesubstrate 30 be formed of a material having substantially the samethermal expansion coefficient as that of the flow-path-forming substrate10; in this embodiment, a single-crystal silicon substrate, which is thesame material as the flow-path-forming substrate 10, is used.

In addition, the drive circuit 120 for driving the piezoelectric element300 is provided on the protective substrate 30. As the drive circuit120, for example, a circuit board, a semiconductor integrated circuit(IC), or the like can be used. The drive circuit 120 and the leadelectrode 90 are electrically connected to each other through theconnection wire 121 formed of a conductive wire such as a bonding wire.

Furthermore, a compliance substrate 40 formed of a sealing film 41 and afixing plate 42 is joined to a region of the protective substrate 30corresponding to the manifold portion 31. The sealing film 41 is formedof a material having low rigidity and flexibility (for example, apolyphenylene sulfide (PPS) film having a thickness of 6 μm), and onesurface of the manifold portion 31 is sealed by the sealing film 41. Inaddition, the fixing plate 42 is formed of a hard material such as ametal (for example, stainless steel (SUS) having a thickness of 30 μm orthe like). Because the area of the fixing plate 42 facing the manifoldportion 31 is an opening portion 43 completely removed in the thicknessdirection, one surface of the manifold portion 31 is a complianceportion sealed only with the sealing film 41 that is flexible.

In the ink jet recording head 1 of this embodiment such as thatdescribed above, ink is taken in from an external ink supply unit (notillustrated), the interior of each of the pressure-generating chambers12 is filled with ink from the manifold portion 31 to the nozzle 21, andthen, in accordance with the recording signal from the drive circuit120, a voltage is applied between the first electrode 60 and the secondelectrode 80 corresponding to the pressure-generating chamber 12, and,by bending and deforming the piezoelectric element 300 and the vibrationplate 50, the pressure in the pressure-generating chamber 12 increases,and ink is discharged from the nozzle 21.

As described above, in this embodiment, a piezoelectric device for usein the recording head 1 which is an example of a liquid ejecting headfor ejecting ink as a liquid from the nozzles 21 includes theflow-path-forming substrate 10 that forms individual liquid chambersincluding the pressure-generating chambers 12 that communicate with thenozzles 21, and the communication portion 13, which serves as a liquidsupply chamber communicating with individual flow paths, the vibrationplate 50 formed at a position corresponding to the individual liquidchambers including the pressure-generating chambers 12 and thecommunication portion 13 of the flow-path-forming substrate 10, aplurality of the liquid supply ports 16 formed in the communicationportion 13, the piezoelectric elements 300 each including the firstelectrode 60, the piezoelectric layer 70, and the second electrode 80,the piezoelectric elements 300 being formed at a position on thevibration plate 50 corresponding to the individual liquid chambersincluding the pressure-generating chambers 12, where the liquid supplyports 16 are provided so as to penetrate the vibration plate 50, and thevibration plate 50 contains zirconium oxide.

By providing the vibration plate 50 including zirconium oxide as thevibration plate 50 provided with the plurality of the liquid supplyports 16 in this manner, it is possible to improve the toughness of thevibration plate 50 and to suppress the occurrence of damage such ascracks and the like in the vibration plate 50 around the plurality ofthe liquid supply ports 16. In addition, because the vibration plate 50can be made thinner as compared with stacking the vibration plate 50 inmultiple layers such as 3 to 10 layers, it is possible to restrain thevibration plate 50 from impeding the flexure of the piezoelectricelement 300 and to suppress the decrease in the displacement of thepiezoelectric element 300.

In addition, in this embodiment, at a position of the vibration plate 50corresponding to the communication portion 13, the crystal structure ofzirconium oxide preferably contains tetragonal crystals or cubiccrystals. In particular, it is preferable that the vibration plate 50further contain yttrium at a position of the vibration plate 50corresponding to the communication portion 13. That is, by usingstabilized (partially stabilized) zirconia as the vibration plate 50,the tetragonal system or the cubic system can be stabilized even at roomtemperature, the toughness of the vibration plate 50 can be furtherenhanced, and it is possible to suppress damage to the vibration plate50 around the liquid supply ports 16.

In addition, it is preferable that the vibration plate 50, at a positioncorresponding to the communication portion 13, have the elastic film 51,which is a compressive stress film in which the internal stress is acompressive stress, and the liquid supply ports 16 penetrate thevibration plate 50 having the elastic film 51. Accordingly, by providingthe elastic film 51, which has a compressive stress as the internalstress, in the vibration plate 50, the internal stress of the vibrationplate 50 around the liquid supply ports 16 can be adjusted and it ispossible to further suppress damage, such as cracks and the like, to thevibration plate 50 around the liquid supply ports.

In addition, the zirconium oxide preferably contains granular crystals.Accordingly, the zirconium oxide can be made to be a flexible filmhaving a small Young's modulus, and the displacement amount of thevibration plate 50 can be increased.

In addition, it is preferable that the vibration plate 50 have theelastic film 51 which is a film containing zirconium oxide and theelastic film 51 be continuously formed in the circumferential directionof the liquid supply ports 16. That is, it is preferable that theelastic film 51 containing zirconium oxide forming the vibration plate50 be continuously formed in the circumferential direction of the liquidsupply ports 16. Accordingly, by providing the vibration plate 50,particularly the insulating film 52 continuously around the liquidsupply ports 16, it is possible to further suppress the formation ofcracks in the vibration plate 50 around the liquid supply ports 16.

Other Embodiments

Although an embodiment of the invention has been described above, thebasic configuration of the invention is not limited to that describedabove.

In addition, for example, in the embodiment described above, aconfiguration in which the protective film 200 that covers thepiezoelectric element 300 is not provided in the region where the liquidsupply ports 16 are formed is exemplified, but this invention is notlimited thereto and the protective film 200 may be provided in theregion where the liquid supply ports 16 are provided. That is, in theregion between the manifold portion 31 and the communication portion 13,the vibration plate 50, and the protective film 200 are stacked, and theliquid supply ports 16 may be provided so as to penetrate through thevibration plate 50, and the protective film 200.

In addition, in the above-described embodiment, the communicationportion 13, which is the liquid supply chamber, is provided so as tocommunicate with all the individual flow paths in common, but thisinvention is not particularly limited thereto and the communicationportion 13 may be provided for each individual flow path or it may beprovided so as to communicate with a group of two or more individualflow paths. However, even when the communication portion 13 is providedfor each individual flow path, there is no limitation regarding thecommunication portion 13 as long as two or more liquid supply ports 16are provided for each communication portion 13. In addition, in the casewhere the communication portion 13 communicates with each individualflow path or each group of two or more individual flow paths, becausethe flow path resistance is dictated by the liquid supply port 16, forexample, the ink supply paths 14 and the communication paths 15 need notbe provided in the flow-path-forming substrate 10. Of course, in each ofthe above-described embodiments, at least one of the ink supply paths 14and the communication paths 15 may be omitted.

Furthermore, in the above-described embodiment, the configuration inwhich the vibration plate 50 is deposited on the flow-path-formingsubstrate 10 has been exemplified, but it is not particularly limitedthereto, and the vibration plate 50 may be joined to theflow-path-forming substrate 10.

In addition, in the above-described embodiment, the piezoelectricelement 300 of the thin-film type is used as a pressure-generatingelement that causes a pressure change in the pressure-generatingchambers 12; however, the invention is not limited thereto, and, forexample, a thick-film piezoelectric element formed by a method such asattaching a green sheet or the like, a longitudinal vibration typepiezoelectric element in which a piezoelectric material and an electrodeforming material are alternately stacked and which expands and contractsin the axial direction, or the like can be used.

In addition, the ink jet recording head 1 constitutes a unit of an inkjet recording head unit having ink flow paths communicating with inkcartridges or the like, and is mounted in an ink jet recordingapparatus. FIG. 5 is a schematic diagram illustrating an example of anink jet recording apparatus.

In the ink jet recording apparatus I illustrated in FIG. 5, a pluralityof the recording heads 1 are detachably provided with ink cartridges 2constituting ink supply units, and a carriage 3 on which the recordingheads 1 are mounted is attached to an apparatus main body 4 and isprovided so as to be movable in the axial direction on a carriage shaft5.

The driving force of a driving motor 6 is transmitted to the carriage 3through a plurality of gears (not illustrated) and a timing belt 7,whereby the carriage 3 on which the recording head 1 is mounted is movedalong the carriage shaft 5. On the other hand, the apparatus main body 4is provided with a transport roller 8 as a mode of transport, and arecording sheet S, which is a recording medium such as paper, istransported by the transport roller 8. Further, the mode of transportfor transporting the recording sheet S is not limited to a transportroller and may be a belt, a drum, or the like.

Further, in the above-described ink jet recording apparatus I, the inkcartridges 2 as ink supply units are mounted on the carriage 3, but theinvention is not particularly limited thereto, and for example, an inksupply unit such as an ink tank may be fixed to the apparatus main body4 and the ink supply unit and the recording head 1 may be connected viaa supply pipe such as a tube. In addition, the ink supply unit need notbe mounted in the ink jet recording apparatus.

In addition, in the ink jet recording apparatus I described above, therecording heads 1 are mounted on the carriage 3 and move in the mainscanning direction; however, this invention is not limited thereto, forexample, the invention can also be applied to a so-called line typerecording apparatus in which the recording heads 1 are fixed andprinting is performed by simply moving the recording sheet

-   -   such as paper in the sub-scanning direction.

Furthermore, the invention is broadly applicable to liquid ejectingheads in general, and is used for manufacturing recording heads such asvarious ink jet recording heads used in image recording apparatuses suchas printers, color material ejecting heads used for manufacturing colorfilters of liquid crystal displays and the like, electrode materialejecting heads used for forming electrodes of organic EL displays, fieldemission displays (FEDs), and the like, bioorganic material ejectingheads used for manufacturing biochips, and the like. In addition,although the ink jet recording apparatus I has been described as anexample of a liquid ejecting apparatus, it can also be used as a liquidejecting apparatus using another of the above-described liquid ejectingheads.

The entire disclosure of Japanese Patent Application No. 2017-132519,filed Jul. 6, 2017 and No. 2018-78914, filed Apr. 17, 2018 are expresslyincorporated by reference herein.

What is claimed is:
 1. A piezoelectric device used in a liquid ejectinghead that ejects a liquid from a nozzle, comprising: a flow-path-formingsubstrate in which an individual liquid chamber that communicates withthe nozzle and a liquid supply chamber that communicates with theindividual liquid chamber are formed, a vibration plate formed at aposition corresponding to the individual liquid chamber and the liquidsupply chamber of the flow-path-forming substrate, a plurality of liquidsupply ports formed in the liquid supply chamber, and a piezoelectricelement including a first electrode, a piezoelectric layer, and a secondelectrode, the piezoelectric element being formed at a position on thevibration plate corresponding to the individual liquid chamber, whereinthe liquid supply ports are provided so as to penetrate the vibrationplate, and wherein the vibration plate contains zirconium oxide.
 2. Thepiezoelectric device according to claim 1, wherein a crystal structureof the zirconium oxide includes a tetragonal crystal or a cubic crystal.3. The piezoelectric device according to claim 2, wherein the vibrationplate further contains yttrium.
 4. The piezoelectric device according toclaim 1, wherein the vibration plate, at a position corresponding to theliquid supply chamber, has a compressive stress film in which aninternal stress is a compressive stress, and wherein the liquid supplyports are provided so as to penetrate the vibration plate having thecompressive stress film.
 5. The piezoelectric device according to claim1, wherein the zirconium oxide contains granular crystals.
 6. Thepiezoelectric device according to claim 1, wherein the vibration platehas a film containing the zirconium oxide and the film containing thezirconium oxide is continuously formed in a circumferential direction ofthe liquid supply ports.
 7. A liquid ejecting head comprising thepiezoelectric device according to claim
 1. 8. A liquid ejecting headcomprising the piezoelectric device according to claim
 2. 9. A liquidejecting head comprising the piezoelectric device according to claim 3.10. A liquid ejecting head comprising the piezoelectric device accordingto claim
 4. 11. A liquid ejecting head comprising the piezoelectricdevice according to claim
 5. 12. A liquid ejecting head comprising thepiezoelectric device according to claim
 6. 13. A liquid ejectingapparatus comprising the liquid ejecting head according to claim
 7. 14.A liquid ejecting apparatus comprising the liquid ejecting headaccording to claim
 8. 15. A liquid ejecting apparatus comprising theliquid ejecting head according to claim
 9. 16. A liquid ejectingapparatus comprising the liquid ejecting head according to claim
 10. 17.A liquid ejecting apparatus comprising the liquid ejecting headaccording to claim
 11. 18. A liquid ejecting apparatus comprising theliquid ejecting head according to claim 12.